#ifndef _ASM_IA64_FCNTL_H
#define _ASM_IA64_FCNTL_H
/*
 * Modified 1998-2000
 *	David Mosberger-Tang <davidm@hpl.hp.com>, Hewlett-Packard Co.
 */

#define force_o_largefile()	\
		(personality(current->personality) != PER_LINUX32)

#include <asm-generic/fcntl.h>

#endif /* _ASM_IA64_FCNTL_H */
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<tr><td class='sub'>User-space crypto API development for Linux</td><td class='sub right'>Miloslav Trmac</td></tr></table>
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<a id='n330' href='#n330'>330</a>
<a id='n331' href='#n331'>331</a>
<a id='n332' href='#n332'>332</a>
<a id='n333' href='#n333'>333</a>
<a id='n334' href='#n334'>334</a>
<a id='n335' href='#n335'>335</a>
<a id='n336' href='#n336'>336</a>
<a id='n337' href='#n337'>337</a>
<a id='n338' href='#n338'>338</a>
<a id='n339' href='#n339'>339</a>
<a id='n340' href='#n340'>340</a>
<a id='n341' href='#n341'>341</a>
<a id='n342' href='#n342'>342</a>
<a id='n343' href='#n343'>343</a>
<a id='n344' href='#n344'>344</a>
<a id='n345' href='#n345'>345</a>
<a id='n346' href='#n346'>346</a>
<a id='n347' href='#n347'>347</a>
<a id='n348' href='#n348'>348</a>
<a id='n349' href='#n349'>349</a>
<a id='n350' href='#n350'>350</a>
<a id='n351' href='#n351'>351</a>
<a id='n352' href='#n352'>352</a>
<a id='n353' href='#n353'>353</a>
<a id='n354' href='#n354'>354</a>
<a id='n355' href='#n355'>355</a>
<a id='n356' href='#n356'>356</a>
<a id='n357' href='#n357'>357</a>
<a id='n358' href='#n358'>358</a>
<a id='n359' href='#n359'>359</a>
<a id='n360' href='#n360'>360</a>
<a id='n361' href='#n361'>361</a>
<a id='n362' href='#n362'>362</a>
<a id='n363' href='#n363'>363</a>
<a id='n364' href='#n364'>364</a>
<a id='n365' href='#n365'>365</a>
<a id='n366' href='#n366'>366</a>
<a id='n367' href='#n367'>367</a>
<a id='n368' href='#n368'>368</a>
<a id='n369' href='#n369'>369</a>
<a id='n370' href='#n370'>370</a>
<a id='n371' href='#n371'>371</a>
<a id='n372' href='#n372'>372</a>
<a id='n373' href='#n373'>373</a>
<a id='n374' href='#n374'>374</a>
<a id='n375' href='#n375'>375</a>
<a id='n376' href='#n376'>376</a>
<a id='n377' href='#n377'>377</a>
<a id='n378' href='#n378'>378</a>
<a id='n379' href='#n379'>379</a>
<a id='n380' href='#n380'>380</a>
<a id='n381' href='#n381'>381</a>
<a id='n382' href='#n382'>382</a>
<a id='n383' href='#n383'>383</a>
<a id='n384' href='#n384'>384</a>
<a id='n385' href='#n385'>385</a>
<a id='n386' href='#n386'>386</a>
<a id='n387' href='#n387'>387</a>
<a id='n388' href='#n388'>388</a>
<a id='n389' href='#n389'>389</a>
<a id='n390' href='#n390'>390</a>
<a id='n391' href='#n391'>391</a>
<a id='n392' href='#n392'>392</a>
<a id='n393' href='#n393'>393</a>
<a id='n394' href='#n394'>394</a>
<a id='n395' href='#n395'>395</a>
<a id='n396' href='#n396'>396</a>
<a id='n397' href='#n397'>397</a>
<a id='n398' href='#n398'>398</a>
<a id='n399' href='#n399'>399</a>
<a id='n400' href='#n400'>400</a>
<a id='n401' href='#n401'>401</a>
<a id='n402' href='#n402'>402</a>
<a id='n403' href='#n403'>403</a>
<a id='n404' href='#n404'>404</a>
<a id='n405' href='#n405'>405</a>
<a id='n406' href='#n406'>406</a>
<a id='n407' href='#n407'>407</a>
<a id='n408' href='#n408'>408</a>
<a id='n409' href='#n409'>409</a>
<a id='n410' href='#n410'>410</a>
<a id='n411' href='#n411'>411</a>
<a id='n412' href='#n412'>412</a>
<a id='n413' href='#n413'>413</a>
<a id='n414' href='#n414'>414</a>
<a id='n415' href='#n415'>415</a>
<a id='n416' href='#n416'>416</a>
<a id='n417' href='#n417'>417</a>
<a id='n418' href='#n418'>418</a>
<a id='n419' href='#n419'>419</a>
<a id='n420' href='#n420'>420</a>
<a id='n421' href='#n421'>421</a>
<a id='n422' href='#n422'>422</a>
<a id='n423' href='#n423'>423</a>
<a id='n424' href='#n424'>424</a>
<a id='n425' href='#n425'>425</a>
<a id='n426' href='#n426'>426</a>
<a id='n427' href='#n427'>427</a>
<a id='n428' href='#n428'>428</a>
<a id='n429' href='#n429'>429</a>
<a id='n430' href='#n430'>430</a>
<a id='n431' href='#n431'>431</a>
<a id='n432' href='#n432'>432</a>
<a id='n433' href='#n433'>433</a>
<a id='n434' href='#n434'>434</a>
<a id='n435' href='#n435'>435</a>
<a id='n436' href='#n436'>436</a>
<a id='n437' href='#n437'>437</a>
<a id='n438' href='#n438'>438</a>
<a id='n439' href='#n439'>439</a>
<a id='n440' href='#n440'>440</a>
<a id='n441' href='#n441'>441</a>
<a id='n442' href='#n442'>442</a>
<a id='n443' href='#n443'>443</a>
<a id='n444' href='#n444'>444</a>
<a id='n445' href='#n445'>445</a>
<a id='n446' href='#n446'>446</a>
<a id='n447' href='#n447'>447</a>
<a id='n448' href='#n448'>448</a>
<a id='n449' href='#n449'>449</a>
<a id='n450' href='#n450'>450</a>
<a id='n451' href='#n451'>451</a>
<a id='n452' href='#n452'>452</a>
<a id='n453' href='#n453'>453</a>
<a id='n454' href='#n454'>454</a>
<a id='n455' href='#n455'>455</a>
<a id='n456' href='#n456'>456</a>
<a id='n457' href='#n457'>457</a>
<a id='n458' href='#n458'>458</a>
<a id='n459' href='#n459'>459</a>
<a id='n460' href='#n460'>460</a>
<a id='n461' href='#n461'>461</a>
<a id='n462' href='#n462'>462</a>
<a id='n463' href='#n463'>463</a>
<a id='n464' href='#n464'>464</a>
<a id='n465' href='#n465'>465</a>
<a id='n466' href='#n466'>466</a>
<a id='n467' href='#n467'>467</a>
<a id='n468' href='#n468'>468</a>
<a id='n469' href='#n469'>469</a>
<a id='n470' href='#n470'>470</a>
<a id='n471' href='#n471'>471</a>
<a id='n472' href='#n472'>472</a>
<a id='n473' href='#n473'>473</a>
<a id='n474' href='#n474'>474</a>
<a id='n475' href='#n475'>475</a>
<a id='n476' href='#n476'>476</a>
<a id='n477' href='#n477'>477</a>
<a id='n478' href='#n478'>478</a>
<a id='n479' href='#n479'>479</a>
<a id='n480' href='#n480'>480</a>
<a id='n481' href='#n481'>481</a>
<a id='n482' href='#n482'>482</a>
<a id='n483' href='#n483'>483</a>
<a id='n484' href='#n484'>484</a>
<a id='n485' href='#n485'>485</a>
<a id='n486' href='#n486'>486</a>
<a id='n487' href='#n487'>487</a>
<a id='n488' href='#n488'>488</a>
<a id='n489' href='#n489'>489</a>
<a id='n490' href='#n490'>490</a>
<a id='n491' href='#n491'>491</a>
<a id='n492' href='#n492'>492</a>
<a id='n493' href='#n493'>493</a>
<a id='n494' href='#n494'>494</a>
<a id='n495' href='#n495'>495</a>
<a id='n496' href='#n496'>496</a>
<a id='n497' href='#n497'>497</a>
<a id='n498' href='#n498'>498</a>
<a id='n499' href='#n499'>499</a>
<a id='n500' href='#n500'>500</a>
<a id='n501' href='#n501'>501</a>
<a id='n502' href='#n502'>502</a>
<a id='n503' href='#n503'>503</a>
<a id='n504' href='#n504'>504</a>
<a id='n505' href='#n505'>505</a>
<a id='n506' href='#n506'>506</a>
<a id='n507' href='#n507'>507</a>
<a id='n508' href='#n508'>508</a>
<a id='n509' href='#n509'>509</a>
<a id='n510' href='#n510'>510</a>
<a id='n511' href='#n511'>511</a>
<a id='n512' href='#n512'>512</a>
<a id='n513' href='#n513'>513</a>
<a id='n514' href='#n514'>514</a>
<a id='n515' href='#n515'>515</a>
<a id='n516' href='#n516'>516</a>
<a id='n517' href='#n517'>517</a>
<a id='n518' href='#n518'>518</a>
<a id='n519' href='#n519'>519</a>
<a id='n520' href='#n520'>520</a>
<a id='n521' href='#n521'>521</a>
<a id='n522' href='#n522'>522</a>
<a id='n523' href='#n523'>523</a>
<a id='n524' href='#n524'>524</a>
<a id='n525' href='#n525'>525</a>
<a id='n526' href='#n526'>526</a>
<a id='n527' href='#n527'>527</a>
<a id='n528' href='#n528'>528</a>
<a id='n529' href='#n529'>529</a>
<a id='n530' href='#n530'>530</a>
<a id='n531' href='#n531'>531</a>
<a id='n532' href='#n532'>532</a>
<a id='n533' href='#n533'>533</a>
<a id='n534' href='#n534'>534</a>
<a id='n535' href='#n535'>535</a>
<a id='n536' href='#n536'>536</a>
<a id='n537' href='#n537'>537</a>
<a id='n538' href='#n538'>538</a>
<a id='n539' href='#n539'>539</a>
<a id='n540' href='#n540'>540</a>
<a id='n541' href='#n541'>541</a>
<a id='n542' href='#n542'>542</a>
<a id='n543' href='#n543'>543</a>
<a id='n544' href='#n544'>544</a>
<a id='n545' href='#n545'>545</a>
<a id='n546' href='#n546'>546</a>
<a id='n547' href='#n547'>547</a>
<a id='n548' href='#n548'>548</a>
<a id='n549' href='#n549'>549</a>
<a id='n550' href='#n550'>550</a>
<a id='n551' href='#n551'>551</a>
<a id='n552' href='#n552'>552</a>
<a id='n553' href='#n553'>553</a>
<a id='n554' href='#n554'>554</a>
<a id='n555' href='#n555'>555</a>
<a id='n556' href='#n556'>556</a>
<a id='n557' href='#n557'>557</a>
<a id='n558' href='#n558'>558</a>
<a id='n559' href='#n559'>559</a>
<a id='n560' href='#n560'>560</a>
<a id='n561' href='#n561'>561</a>
<a id='n562' href='#n562'>562</a>
<a id='n563' href='#n563'>563</a>
<a id='n564' href='#n564'>564</a>
<a id='n565' href='#n565'>565</a>
<a id='n566' href='#n566'>566</a>
<a id='n567' href='#n567'>567</a>
<a id='n568' href='#n568'>568</a>
<a id='n569' href='#n569'>569</a>
<a id='n570' href='#n570'>570</a>
<a id='n571' href='#n571'>571</a>
<a id='n572' href='#n572'>572</a>
<a id='n573' href='#n573'>573</a>
<a id='n574' href='#n574'>574</a>
<a id='n575' href='#n575'>575</a>
<a id='n576' href='#n576'>576</a>
<a id='n577' href='#n577'>577</a>
<a id='n578' href='#n578'>578</a>
<a id='n579' href='#n579'>579</a>
<a id='n580' href='#n580'>580</a>
<a id='n581' href='#n581'>581</a>
<a id='n582' href='#n582'>582</a>
<a id='n583' href='#n583'>583</a>
<a id='n584' href='#n584'>584</a>
<a id='n585' href='#n585'>585</a>
<a id='n586' href='#n586'>586</a>
<a id='n587' href='#n587'>587</a>
<a id='n588' href='#n588'>588</a>
<a id='n589' href='#n589'>589</a>
<a id='n590' href='#n590'>590</a>
<a id='n591' href='#n591'>591</a>
<a id='n592' href='#n592'>592</a>
<a id='n593' href='#n593'>593</a>
<a id='n594' href='#n594'>594</a>
<a id='n595' href='#n595'>595</a>
<a id='n596' href='#n596'>596</a>
<a id='n597' href='#n597'>597</a>
<a id='n598' href='#n598'>598</a>
<a id='n599' href='#n599'>599</a>
<a id='n600' href='#n600'>600</a>
<a id='n601' href='#n601'>601</a>
<a id='n602' href='#n602'>602</a>
<a id='n603' href='#n603'>603</a>
<a id='n604' href='#n604'>604</a>
<a id='n605' href='#n605'>605</a>
<a id='n606' href='#n606'>606</a>
<a id='n607' href='#n607'>607</a>
<a id='n608' href='#n608'>608</a>
<a id='n609' href='#n609'>609</a>
<a id='n610' href='#n610'>610</a>
<a id='n611' href='#n611'>611</a>
<a id='n612' href='#n612'>612</a>
<a id='n613' href='#n613'>613</a>
<a id='n614' href='#n614'>614</a>
<a id='n615' href='#n615'>615</a>
<a id='n616' href='#n616'>616</a>
<a id='n617' href='#n617'>617</a>
<a id='n618' href='#n618'>618</a>
<a id='n619' href='#n619'>619</a>
<a id='n620' href='#n620'>620</a>
<a id='n621' href='#n621'>621</a>
<a id='n622' href='#n622'>622</a>
<a id='n623' href='#n623'>623</a>
<a id='n624' href='#n624'>624</a>
<a id='n625' href='#n625'>625</a>
<a id='n626' href='#n626'>626</a>
<a id='n627' href='#n627'>627</a>
<a id='n628' href='#n628'>628</a>
<a id='n629' href='#n629'>629</a>
<a id='n630' href='#n630'>630</a>
<a id='n631' href='#n631'>631</a>
<a id='n632' href='#n632'>632</a>
<a id='n633' href='#n633'>633</a>
<a id='n634' href='#n634'>634</a>
<a id='n635' href='#n635'>635</a>
<a id='n636' href='#n636'>636</a>
<a id='n637' href='#n637'>637</a>
<a id='n638' href='#n638'>638</a>
<a id='n639' href='#n639'>639</a>
<a id='n640' href='#n640'>640</a>
<a id='n641' href='#n641'>641</a>
<a id='n642' href='#n642'>642</a>
<a id='n643' href='#n643'>643</a>
<a id='n644' href='#n644'>644</a>
<a id='n645' href='#n645'>645</a>
<a id='n646' href='#n646'>646</a>
<a id='n647' href='#n647'>647</a>
<a id='n648' href='#n648'>648</a>
<a id='n649' href='#n649'>649</a>
<a id='n650' href='#n650'>650</a>
<a id='n651' href='#n651'>651</a>
<a id='n652' href='#n652'>652</a>
<a id='n653' href='#n653'>653</a>
<a id='n654' href='#n654'>654</a>
<a id='n655' href='#n655'>655</a>
<a id='n656' href='#n656'>656</a>
<a id='n657' href='#n657'>657</a>
<a id='n658' href='#n658'>658</a>
<a id='n659' href='#n659'>659</a>
<a id='n660' href='#n660'>660</a>
<a id='n661' href='#n661'>661</a>
<a id='n662' href='#n662'>662</a>
<a id='n663' href='#n663'>663</a>
<a id='n664' href='#n664'>664</a>
<a id='n665' href='#n665'>665</a>
<a id='n666' href='#n666'>666</a>
<a id='n667' href='#n667'>667</a>
<a id='n668' href='#n668'>668</a>
<a id='n669' href='#n669'>669</a>
<a id='n670' href='#n670'>670</a>
<a id='n671' href='#n671'>671</a>
<a id='n672' href='#n672'>672</a>
<a id='n673' href='#n673'>673</a>
<a id='n674' href='#n674'>674</a>
<a id='n675' href='#n675'>675</a>
<a id='n676' href='#n676'>676</a>
<a id='n677' href='#n677'>677</a>
<a id='n678' href='#n678'>678</a>
<a id='n679' href='#n679'>679</a>
<a id='n680' href='#n680'>680</a>
<a id='n681' href='#n681'>681</a>
<a id='n682' href='#n682'>682</a>
<a id='n683' href='#n683'>683</a>
<a id='n684' href='#n684'>684</a>
<a id='n685' href='#n685'>685</a>
<a id='n686' href='#n686'>686</a>
<a id='n687' href='#n687'>687</a>
<a id='n688' href='#n688'>688</a>
<a id='n689' href='#n689'>689</a>
<a id='n690' href='#n690'>690</a>
<a id='n691' href='#n691'>691</a>
<a id='n692' href='#n692'>692</a>
<a id='n693' href='#n693'>693</a>
<a id='n694' href='#n694'>694</a>
<a id='n695' href='#n695'>695</a>
<a id='n696' href='#n696'>696</a>
<a id='n697' href='#n697'>697</a>
<a id='n698' href='#n698'>698</a>
<a id='n699' href='#n699'>699</a>
<a id='n700' href='#n700'>700</a>
<a id='n701' href='#n701'>701</a>
<a id='n702' href='#n702'>702</a>
<a id='n703' href='#n703'>703</a>
<a id='n704' href='#n704'>704</a>
<a id='n705' href='#n705'>705</a>
<a id='n706' href='#n706'>706</a>
<a id='n707' href='#n707'>707</a>
<a id='n708' href='#n708'>708</a>
<a id='n709' href='#n709'>709</a>
<a id='n710' href='#n710'>710</a>
<a id='n711' href='#n711'>711</a>
<a id='n712' href='#n712'>712</a>
<a id='n713' href='#n713'>713</a>
<a id='n714' href='#n714'>714</a>
<a id='n715' href='#n715'>715</a>
<a id='n716' href='#n716'>716</a>
<a id='n717' href='#n717'>717</a>
<a id='n718' href='#n718'>718</a>
<a id='n719' href='#n719'>719</a>
<a id='n720' href='#n720'>720</a>
<a id='n721' href='#n721'>721</a>
<a id='n722' href='#n722'>722</a>
<a id='n723' href='#n723'>723</a>
<a id='n724' href='#n724'>724</a>
<a id='n725' href='#n725'>725</a>
<a id='n726' href='#n726'>726</a>
<a id='n727' href='#n727'>727</a>
<a id='n728' href='#n728'>728</a>
<a id='n729' href='#n729'>729</a>
<a id='n730' href='#n730'>730</a>
<a id='n731' href='#n731'>731</a>
<a id='n732' href='#n732'>732</a>
<a id='n733' href='#n733'>733</a>
<a id='n734' href='#n734'>734</a>
<a id='n735' href='#n735'>735</a>
<a id='n736' href='#n736'>736</a>
<a id='n737' href='#n737'>737</a>
<a id='n738' href='#n738'>738</a>
<a id='n739' href='#n739'>739</a>
<a id='n740' href='#n740'>740</a>
<a id='n741' href='#n741'>741</a>
<a id='n742' href='#n742'>742</a>
<a id='n743' href='#n743'>743</a>
<a id='n744' href='#n744'>744</a>
<a id='n745' href='#n745'>745</a>
<a id='n746' href='#n746'>746</a>
<a id='n747' href='#n747'>747</a>
<a id='n748' href='#n748'>748</a>
<a id='n749' href='#n749'>749</a>
<a id='n750' href='#n750'>750</a>
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<td class='lines'><pre><code><span class="hl kwa">\documentclass</span><span class="hl opt">{</span>article<span class="hl opt">}</span>
<span class="hl kwa">\def\version</span><span class="hl opt">{</span>$Id: cdrom-standard.tex,v <span class="hl num">1.9 1997</span>/<span class="hl num">12</span>/<span class="hl num">28 15</span>:<span class="hl num">42</span>:<span class="hl num">49</span> david Exp $<span class="hl opt">}</span>
<span class="hl kwa">\newcommand</span><span class="hl opt">{</span><span class="hl kwa">\newsection</span><span class="hl opt">}[</span><span class="hl num">1</span><span class="hl opt">]{</span><span class="hl kwa">\newpage\section</span><span class="hl opt">{</span><span class="hl kwc">#1</span><span class="hl opt">}}</span>

<span class="hl kwa">\evensidemargin</span>=<span class="hl num">0</span>pt
<span class="hl kwa">\oddsidemargin</span>=<span class="hl num">0</span>pt
<span class="hl kwa">\topmargin</span>=-<span class="hl kwa">\headheight \advance\topmargin</span> by -<span class="hl kwa">\headsep</span>
<span class="hl kwa">\textwidth</span>=<span class="hl num">15.99</span>cm <span class="hl kwa">\textheight</span>=<span class="hl num">24.62</span>cm <span class="hl slc">% normal A4, 1&#39;&#39; margin</span>

<span class="hl kwa">\def\linux</span><span class="hl opt">{{</span><span class="hl kwa">\sc</span> Linux<span class="hl opt">}}</span>
<span class="hl kwa">\def\cdrom</span><span class="hl opt">{{</span><span class="hl kwa">\sc</span> cd-rom<span class="hl opt">}}</span>
<span class="hl kwa">\def\UCD</span><span class="hl opt">{{</span><span class="hl kwa">\sc</span> Uniform cd-rom Driver<span class="hl opt">}}</span>
<span class="hl kwa">\def\cdromc</span><span class="hl opt">{{</span><span class="hl kwa">\tt</span> <span class="hl opt">{</span>cdrom.c<span class="hl opt">}}}</span>
<span class="hl kwa">\def\cdromh</span><span class="hl opt">{{</span><span class="hl kwa">\tt</span> <span class="hl opt">{</span>cdrom.h<span class="hl opt">}}}</span>
<span class="hl kwa">\def\fo</span><span class="hl opt">{</span><span class="hl kwa">\sl</span><span class="hl opt">}</span>                    <span class="hl slc">% foreign words</span>
<span class="hl kwa">\def\ie</span><span class="hl opt">{{</span><span class="hl kwa">\fo</span> i.e.<span class="hl opt">}}</span>
<span class="hl kwa">\def\eg</span><span class="hl opt">{{</span><span class="hl kwa">\fo</span> e.g.<span class="hl opt">}}</span>

<span class="hl kwa">\everymath</span><span class="hl opt">{</span><span class="hl kwa">\it</span><span class="hl opt">}</span> <span class="hl kwa">\everydisplay</span><span class="hl opt">{</span><span class="hl kwa">\it</span><span class="hl opt">}</span>
<span class="hl kwa">\catcode</span> `<span class="hl kwa">\_</span>=<span class="hl kwa">\active \def_</span><span class="hl opt">{</span><span class="hl kwa">\_\penalty100</span> <span class="hl opt">}</span>
<span class="hl kwa">\catcode</span>`\&lt;=<span class="hl kwa">\active \def</span>&lt;<span class="hl kwc">#1</span>&gt;<span class="hl opt">{{</span><span class="hl kwa">\langle\hbox</span><span class="hl opt">{</span><span class="hl kwa">\rm</span><span class="hl kwc">#1</span><span class="hl opt">}</span><span class="hl kwa">\rangle</span><span class="hl opt">}}</span>

<span class="hl kwa">\begin</span><span class="hl opt">{</span><span class="hl kwb">document</span><span class="hl opt">}</span>
<span class="hl kwa">\title</span><span class="hl opt">{</span>A <span class="hl kwa">\linux</span>\ <span class="hl kwa">\cdrom</span>\ standard<span class="hl opt">}</span>
<span class="hl kwa">\author</span><span class="hl opt">{</span>David van Leeuwen\\<span class="hl opt">{</span><span class="hl kwa">\normalsize\tt</span> david&#64;ElseWare.cistron.nl<span class="hl opt">}</span>
\\<span class="hl opt">{</span><span class="hl kwa">\footnotesize</span> updated by Erik Andersen <span class="hl opt">{</span><span class="hl kwa">\tt</span>(andersee&#64;debian.org)<span class="hl opt">}}</span>
\\<span class="hl opt">{</span><span class="hl kwa">\footnotesize</span> updated by Jens Axboe <span class="hl opt">{</span><span class="hl kwa">\tt</span>(axboe&#64;image.dk)<span class="hl opt">}}}</span>
<span class="hl kwa">\date</span><span class="hl opt">{</span><span class="hl num">12</span> March <span class="hl num">1999</span><span class="hl opt">}</span>

<span class="hl kwa">\maketitle</span>

<span class="hl kwa">\newsection</span><span class="hl opt">{</span>Introduction<span class="hl opt">}</span>

<span class="hl kwa">\linux</span>\ is probably the Unix-like operating system that supports
the widest variety of hardware devices. The reasons for this are
presumably 
<span class="hl kwa">\begin</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span> 
<span class="hl kwa">\item</span> 
  The large list of hardware devices available for the many platforms
  that <span class="hl kwa">\linux</span>\ now supports (<span class="hl kwa">\ie</span>, i386-PCs, Sparc Suns, etc.)
<span class="hl kwa">\item</span> 
  The open design of the operating system, such that anybody can write a
  driver for <span class="hl kwa">\linux</span>.
<span class="hl kwa">\item</span> 
  There is plenty of source code around as examples of how to write a driver.
<span class="hl kwa">\end</span><span class="hl opt">{</span>itemize<span class="hl opt">}</span>
The openness of <span class="hl kwa">\linux</span>, and the many different types of available
hardware has allowed <span class="hl kwa">\linux</span>\ to support many different hardware devices.
Unfortunately, the very openness that has allowed <span class="hl kwa">\linux</span>\ to support
all these different devices has also allowed the behavior of each
device driver to differ significantly from one device to another.
This divergence of behavior has been very significant for <span class="hl kwa">\cdrom</span>\
devices; the way a particular drive reacts to a `standard&#39; $ioctl()$
call varies greatly from one device driver to another. To avoid making
their drivers totally inconsistent, the writers of <span class="hl kwa">\linux</span>\ <span class="hl kwa">\cdrom</span>\
drivers generally created new device drivers by understanding, copying,
and then changing an existing one. Unfortunately, this practice did not
maintain uniform behavior across all the <span class="hl kwa">\linux</span>\ <span class="hl kwa">\cdrom</span>\ drivers. 

This <span class="hl kwb">document</span> describes an effort to establish Uniform behavior across
all the different <span class="hl kwa">\cdrom</span>\ device drivers for <span class="hl kwa">\linux</span>. This <span class="hl kwb">document</span> also
defines the various $ioctl$s, and how the low-level <span class="hl kwa">\cdrom</span>\ device
drivers should implement them. Currently (as of the <span class="hl kwa">\linux</span>\ <span class="hl num">2.1</span>.$x$
development kernels) several low-level <span class="hl kwa">\cdrom</span>\ device drivers, including
both IDE/ATAPI and SCSI, now use this Uniform interface.

When the <span class="hl kwa">\cdrom</span>\ was developed, the interface between the <span class="hl kwa">\cdrom</span>\ drive
and the computer was not specified in the standards. As a result, many
different <span class="hl kwa">\cdrom</span>\ interfaces were developed. Some of them had their
own proprietary design (Sony, Mitsumi, Panasonic, Philips), other
manufacturers adopted an existing electrical interface and changed
the functionality (CreativeLabs/SoundBlaster, Teac, Funai) or simply
adapted their drives to one or more of the already existing electrical
interfaces (Aztech, Sanyo, Funai, Vertos, Longshine, Optics Storage and
most of the `NoName&#39; manufacturers). In cases where a new drive really
brought its own interface or used its own command set and flow control
scheme, either a separate driver had to be written, or an existing
driver had to be enhanced. History has delivered us <span class="hl kwa">\cdrom</span>\ support for
many of these different interfaces. Nowadays, almost all new <span class="hl kwa">\cdrom</span>\
drives are either IDE/ATAPI or SCSI, and it is very unlikely that any
manufacturer will create a new interface. Even finding drives for the
old proprietary interfaces is getting difficult.

When (in the <span class="hl num">1.3.70</span>&#39;s) I looked at the existing software interface,
which was expressed through <span class="hl kwa">\cdromh</span>, it appeared to be a rather wild
set of commands and data formats.<span class="hl kwa">\footnote</span><span class="hl opt">{</span>I cannot recollect what
kernel version I looked at, then, presumably <span class="hl num">1.2.13</span> and <span class="hl num">1.3.34</span>---the
latest kernel that I was indirectly involved in.<span class="hl opt">}</span> It seemed that many
features of the software interface had been added to accommodate the
capabilities of a particular drive, in an <span class="hl opt">{</span><span class="hl kwa">\fo</span> ad hoc\/<span class="hl opt">}</span> manner. More
importantly, it appeared that the behavior of the `standard&#39; commands
was different for most of the different drivers: <span class="hl kwa">\eg</span>, some drivers
close the tray if an $open()$ call occurs when the tray is open, while
others do not. Some drivers lock the door upon opening the device, to
prevent an incoherent file system, but others don&#39;t, to allow software
ejection. Undoubtedly, the capabilities of the different drives vary,
but even when two drives have the same capability their drivers&#39;
behavior was usually different.

I decided to start a discussion on how to make all the <span class="hl kwa">\linux</span>\ <span class="hl kwa">\cdrom</span>\
drivers behave more uniformly. I began by contacting the developers of
the many <span class="hl kwa">\cdrom</span>\ drivers found in the <span class="hl kwa">\linux</span>\ kernel. Their reactions
encouraged me to write the <span class="hl kwa">\UCD</span>\ which this <span class="hl kwb">document</span> is intended to
describe. The implementation of the <span class="hl kwa">\UCD</span>\ is in the file <span class="hl kwa">\cdromc</span>. This
driver is intended to be an additional software layer that sits on top
of the low-level device drivers for each <span class="hl kwa">\cdrom</span>\ drive. By adding this
additional layer, it is possible to have all the different <span class="hl kwa">\cdrom</span>\
devices behave <span class="hl opt">{</span><span class="hl kwa">\em</span> exactly\/<span class="hl opt">}</span> the same (insofar as the underlying
hardware will allow).

The goal of the <span class="hl kwa">\UCD</span>\ is <span class="hl opt">{</span><span class="hl kwa">\em</span> not\/<span class="hl opt">}</span> to alienate driver developers who
have not yet taken steps to support this effort. The goal of <span class="hl kwa">\UCD</span>\ is
simply to give people writing application programs for <span class="hl kwa">\cdrom</span>\ drives
<span class="hl opt">{</span><span class="hl kwa">\em</span> one\/<span class="hl opt">}</span> <span class="hl kwa">\linux</span>\ <span class="hl kwa">\cdrom</span>\ interface with consistent behavior for all
<span class="hl kwa">\cdrom</span>\ devices. In addition, this also provides a consistent interface
between the low-level device driver code and the <span class="hl kwa">\linux</span>\ kernel. Care
is taken that <span class="hl num">100</span>\,\% compatibility exists with the data structures and
programmer&#39;s interface defined in <span class="hl kwa">\cdromh</span>. This guide was written to
help <span class="hl kwa">\cdrom</span>\ driver developers adapt their code to use the <span class="hl kwa">\UCD</span>\ code
defined in <span class="hl kwa">\cdromc</span>.

Personally, I think that the most important hardware interfaces are
the IDE/ATAPI drives and, of course, the SCSI drives, but as prices
of hardware drop continuously, it is also likely that people may have
more than one <span class="hl kwa">\cdrom</span>\ drive, possibly of mixed types. It is important
that these drives behave in the same way. In December <span class="hl num">1994</span>, one of the
cheapest <span class="hl kwa">\cdrom</span>\ drives was a Philips cm206, a double-speed proprietary
drive. In the months that I was busy writing a <span class="hl kwa">\linux</span>\ driver for it,
proprietary drives became obsolete and IDE/ATAPI drives became the
standard. At the time of the last update to this <span class="hl kwb">document</span> (November
<span class="hl num">1997</span>) it is becoming difficult to even <span class="hl opt">{</span><span class="hl kwa">\em</span> find<span class="hl opt">}</span> anything less than a
<span class="hl num">16</span> speed <span class="hl kwa">\cdrom</span>\ drive, and <span class="hl num">24</span> speed drives are common.

<span class="hl kwa">\newsection</span><span class="hl opt">{</span>Standardizing through another software level<span class="hl opt">}</span>
<span class="hl kwa">\label</span><span class="hl opt">{</span>cdrom.c<span class="hl opt">}</span>

At the time this <span class="hl kwb">document</span> was conceived, all drivers directly
implemented the <span class="hl kwa">\cdrom</span>\ $ioctl()$ calls through their own routines. This
led to the danger of different drivers forgetting to do important things
like checking that the user was giving the driver valid data. More
importantly, this led to the divergence of behavior, which has already
been discussed.

For this reason, the <span class="hl kwa">\UCD</span>\ was created to enforce consistent <span class="hl kwa">\cdrom</span>\
drive behavior, and to provide a common set of services to the various
low-level <span class="hl kwa">\cdrom</span>\ device drivers. The <span class="hl kwa">\UCD</span>\ now provides another
software-level, that separates the $ioctl()$ and $open()$ implementation
from the actual hardware implementation. Note that this effort has
made few changes which will affect a user&#39;s application programs. The
greatest change involved moving the contents of the various low-level
<span class="hl kwa">\cdrom</span>\ drivers&#39; header files to the kernel&#39;s cdrom directory. This was
done to help ensure that the user is only presented with only one cdrom
interface, the interface defined in <span class="hl kwa">\cdromh</span>.

<span class="hl kwa">\cdrom</span>\ drives are specific enough (<span class="hl kwa">\ie</span>, different from other
block-devices such as floppy or hard disc drives), to define a set
of common <span class="hl opt">{</span><span class="hl kwa">\em \cdrom</span>\ device operations<span class="hl opt">}</span>, $&lt;cdrom-device&gt;_dops$.
These operations are different from the classical block-device file
operations, $&lt;block-device&gt;_fops$.

The routines for the <span class="hl kwa">\UCD</span>\ interface level are implemented in the file
<span class="hl kwa">\cdromc</span>. In this file, the <span class="hl kwa">\UCD</span>\ interfaces with the kernel as a block
device by registering the following general $struct\ file_operations$:
$$
<span class="hl kwa">\halign</span><span class="hl opt">{</span>$#$\ <span class="hl kwa">\hfil</span>&amp;$#$\ <span class="hl kwa">\hfil</span>&amp;$/*$ <span class="hl kwa">\rm</span># $*/$<span class="hl kwa">\hfil\cr</span>
struct&amp; file_operations\ cdrom_fops = \<span class="hl opt">{</span><span class="hl kwa">\hidewidth\cr</span>
        &amp;NULL,                  &amp; lseek <span class="hl kwa">\cr</span>
        &amp;block_read,            &amp; read---general block-dev read <span class="hl kwa">\cr</span>
        &amp;block_write,           &amp; write---general block-dev write <span class="hl kwa">\cr</span>
        &amp;NULL,                  &amp; readdir <span class="hl kwa">\cr</span>
        &amp;NULL,                  &amp; select <span class="hl kwa">\cr</span>
        &amp;cdrom_ioctl,           &amp; ioctl <span class="hl kwa">\cr</span>
        &amp;NULL,                  &amp; mmap <span class="hl kwa">\cr</span>
        &amp;cdrom_open,            &amp; open <span class="hl kwa">\cr</span>
        &amp;cdrom_release,         &amp; release <span class="hl kwa">\cr</span>
        &amp;NULL,                  &amp; fsync <span class="hl kwa">\cr</span>
        &amp;NULL,                  &amp; fasync <span class="hl kwa">\cr</span>
        &amp;cdrom_media_changed,   &amp; media change <span class="hl kwa">\cr</span>
        &amp;NULL                   &amp; revalidate <span class="hl kwa">\cr</span>
\<span class="hl opt">}</span>;<span class="hl kwa">\cr</span>
<span class="hl opt">}</span>
$$ 

Every active <span class="hl kwa">\cdrom</span>\ device shares this $struct$. The routines
declared above are all implemented in <span class="hl kwa">\cdromc</span>, since this file is the
place where the behavior of all <span class="hl kwa">\cdrom</span>-devices is defined and
standardized. The actual interface to the various types of <span class="hl kwa">\cdrom</span>\ 
hardware is still performed by various low-level <span class="hl kwa">\cdrom</span>-device
drivers. These routines simply implement certain <span class="hl opt">{</span><span class="hl kwa">\em</span> capabilities\/<span class="hl opt">}</span>
that are common to all <span class="hl kwa">\cdrom</span>\ (and really, all removable-media
devices).

Registration of a low-level <span class="hl kwa">\cdrom</span>\ device driver is now done through
the general routines in <span class="hl kwa">\cdromc</span>, not through the Virtual File System
(VFS) any more. The interface implemented in <span class="hl kwa">\cdromc</span>\ is carried out
through two general structures that contain information about the
capabilities of the driver, and the specific drives on which the
driver operates. The structures are:
<span class="hl kwa">\begin</span><span class="hl opt">{</span>description<span class="hl opt">}</span>
<span class="hl kwa">\item</span><span class="hl opt">[</span>$cdrom_device_ops$<span class="hl opt">]</span> 
  This structure contains information about the low-level driver for a
  <span class="hl kwa">\cdrom</span>\ device. This structure is conceptually connected to the major
  number of the device (although some drivers may have different
  major numbers, as is the case for the IDE driver).
<span class="hl kwa">\item</span><span class="hl opt">[</span>$cdrom_device_info$<span class="hl opt">]</span> 
  This structure contains information about a particular <span class="hl kwa">\cdrom</span>\ drive,
  such as its device name, speed, etc. This structure is conceptually
  connected to the minor number of the device.
<span class="hl kwa">\end</span><span class="hl opt">{</span>description<span class="hl opt">}</span>

Registering a particular <span class="hl kwa">\cdrom</span>\ drive with the <span class="hl kwa">\UCD</span>\ is done by the
low-level device driver though a call to:
$$register_cdrom(struct\ cdrom_device_info * &lt;device&gt;_info)  
$$
The device information structure, $&lt;device&gt;_info$, contains all the
information needed for the kernel to interface with the low-level
<span class="hl kwa">\cdrom</span>\ device driver. One of the most important entries in this
structure is a pointer to the $cdrom_device_ops$ structure of the
low-level driver.

The device operations structure, $cdrom_device_ops$, contains a list
of pointers to the functions which are implemented in the low-level
device driver. When <span class="hl kwa">\cdromc</span>\ accesses a <span class="hl kwa">\cdrom</span>\ device, it does it
through the functions in this structure. It is impossible to know all
the capabilities of future <span class="hl kwa">\cdrom</span>\ drives, so it is expected that this
list may need to be expanded from time to time as new technologies are
developed. For example, CD-R and CD-R/W drives are beginning to become
popular, and support will soon need to be added for them. For now, the
current $struct$ is:
$$
<span class="hl kwa">\halign</span><span class="hl opt">{</span>$#$\ <span class="hl kwa">\hfil</span>&amp;$#$\ <span class="hl kwa">\hfil</span>&amp;<span class="hl kwa">\hbox</span> to <span class="hl num">10</span>em<span class="hl opt">{</span>$#$<span class="hl kwa">\hss</span><span class="hl opt">}</span>&amp;
  $/*$ <span class="hl kwa">\rm</span># $*/$<span class="hl kwa">\hfil\cr</span>
struct&amp; cdrom_device_ops\ \<span class="hl opt">{</span> <span class="hl kwa">\hidewidth\cr</span>
  &amp;int&amp; <span class="hl com">(* open)(struct\ cdrom_device_info *, int)\cr</span>
<span class="hl com">  &amp;void&amp; (* release)(struct\ cdrom_device_info *)</span>;<span class="hl kwa">\cr</span> 
  &amp;int&amp; <span class="hl com">(* drive_status)(struct\ cdrom_device_info *, int);\cr     </span>
<span class="hl com">  &amp;int&amp; (* media_changed)(struct\ cdrom_device_info *, int);\cr </span>
<span class="hl com">  &amp;int&amp; (* tray_move)(struct\ cdrom_device_info *, int);\cr</span>
<span class="hl com">  &amp;int&amp; (* lock_door)(struct\ cdrom_device_info *, int);\cr</span>
<span class="hl com">  &amp;int&amp; (* select_speed)(struct\ cdrom_device_info *, int);\cr</span>
<span class="hl com">  &amp;int&amp; (* select_disc)(struct\ cdrom_device_info *, int);\cr</span>
<span class="hl com">  &amp;int&amp; (* get_last_session) (struct\ cdrom_device_info *, </span>
<span class="hl com">        struct\ cdrom_multisession *{});\cr</span>
<span class="hl com">  &amp;int&amp; (* get_mcn)(struct\ cdrom_device_info *, struct\ cdrom_mcn *{});\cr</span>
<span class="hl com">  &amp;int&amp; (* reset)(struct\ cdrom_device_info *)</span>;<span class="hl kwa">\cr</span>
  &amp;int&amp; <span class="hl com">(* audio_ioctl)(struct\ cdrom_device_info *, unsigned\ int, </span>
<span class="hl com">        void *{});\cr </span>
<span class="hl com">  &amp;int&amp; (* dev_ioctl)(struct\ cdrom_device_info *, unsigned\ int, </span>
<span class="hl com">        unsigned\ long);\cr</span>
<span class="hl com">\noalign{\medskip}</span>
<span class="hl com">  &amp;const\ int&amp; capability;&amp; capability flags \cr</span>
<span class="hl com">  &amp;int&amp; n_minors;&amp; number of active minor devices \cr</span>
<span class="hl com">\};\cr</span>
<span class="hl com">}</span>
<span class="hl com">$$</span>
<span class="hl com">When a low-level device driver implements one of these capabilities,</span>
<span class="hl com">it should add a function pointer to this $struct$. When a particular</span>
<span class="hl com">function is not implemented, however, this $struct$ should contain a</span>
<span class="hl com">NULL instead. The $capability$ flags specify the capabilities of the</span>
<span class="hl com">\cdrom\ hardware and/or low-level \cdrom\ driver when a \cdrom\ drive</span>
<span class="hl com">is registered with the \UCD. The value $n_minors$ should be a positive</span>
<span class="hl com">value indicating the number of minor devices that are supported by</span>
<span class="hl com">the low-level device driver, normally~1. Although these two variables</span>
<span class="hl com">are `informative&#39; rather than `operational,&#39; they are included in</span>
<span class="hl com">$cdrom_device_ops$ because they describe the capability of the {\em</span>
<span class="hl com">driver\/} rather than the {\em drive}. Nomenclature has always been</span>
<span class="hl com">difficult in computer programming.</span>
<span class="hl com"></span>
<span class="hl com">Note that most functions have fewer parameters than their</span>
<span class="hl com">$blkdev_fops$ counterparts. This is because very little of the</span>
<span class="hl com">information in the structures $inode$ and $file$ is used. For most</span>
<span class="hl com">drivers, the main parameter is the $struct$ $cdrom_device_info$, from</span>
<span class="hl com">which the major and minor number can be extracted. (Most low-level</span>
<span class="hl com">\cdrom\ drivers don&#39;t even look at the major and minor number though,</span>
<span class="hl com">since many of them only support one device.) This will be available</span>
<span class="hl com">through $dev$ in $cdrom_device_info$ described below.</span>
<span class="hl com"></span>
<span class="hl com">The drive-specific, minor-like information that is registered with</span>
<span class="hl com">\cdromc, currently contains the following fields:</span>
<span class="hl com">$$</span>
<span class="hl com">\halign{$#$\ \hfil&amp;$#$\ \hfil&amp;\hbox to 10em{$#$\hss}&amp;</span>
<span class="hl com">  $/*$ \rm# $*/$\hfil\cr</span>
<span class="hl com">struct&amp; cdrom_device_info\ \{ \hidewidth\cr</span>
<span class="hl com">  &amp; struct\ cdrom_device_ops *&amp; ops;&amp; device operations for this major\cr</span>
<span class="hl com">  &amp; struct\ cdrom_device_info *&amp; next;&amp; next device_info for this major\cr</span>
<span class="hl com">  &amp; void *&amp;  handle;&amp; driver-dependent data\cr</span>
<span class="hl com">\noalign{\medskip}</span>
<span class="hl com">  &amp; kdev_t&amp;  dev;&amp; device number (incorporates minor)\cr</span>
<span class="hl com">  &amp; int&amp; mask;&amp; mask of capability: disables them \cr</span>
<span class="hl com">  &amp; int&amp; speed;&amp; maximum speed for reading data \cr</span>
<span class="hl com">  &amp; int&amp; capacity;&amp; number of discs in a jukebox \cr</span>
<span class="hl com">\noalign{\medskip}</span>
<span class="hl com">  &amp;int&amp; options : 30;&amp; options flags \cr</span>
<span class="hl com">  &amp;unsigned&amp; mc_flags : 2;&amp; media-change buffer flags \cr</span>
<span class="hl com">  &amp; int&amp; use_count;&amp; number of times device is opened\cr</span>
<span class="hl com">  &amp; char&amp; name[20];&amp; name of the device type\cr</span>
<span class="hl com">\}\cr</span>
<span class="hl com">}$$</span>
<span class="hl com">Using this $struct$, a linked list of the registered minor devices is</span>
<span class="hl com">built, using the $next$ field. The device number, the device operations</span>
<span class="hl com">struct and specifications of properties of the drive are stored in this</span>
<span class="hl com">structure.</span>
<span class="hl com"></span>
<span class="hl com">The $mask$ flags can be used to mask out some of the capabilities listed</span>
<span class="hl com">in $ops\to capability$, if a specific drive doesn&#39;t support a feature</span>
<span class="hl com">of the driver. The value $speed$ specifies the maximum head-rate of the</span>
<span class="hl com">drive, measured in units of normal audio speed (176\,kB/sec raw data or</span>
<span class="hl com">150\,kB/sec file system data). The value $n_discs$ should reflect the</span>
<span class="hl com">number of discs the drive can hold simultaneously, if it is designed</span>
<span class="hl com">as a juke-box, or otherwise~1. The parameters are declared $const$</span>
<span class="hl com">because they describe properties of the drive, which don&#39;t change after</span>
<span class="hl com">registration.</span>
<span class="hl com"></span>
<span class="hl com">A few registers contain variables local to the \cdrom\ drive. The</span>
<span class="hl com">flags $options$ are used to specify how the general \cdrom\ routines</span>
<span class="hl com">should behave. These various flags registers should provide enough</span>
<span class="hl com">flexibility to adapt to the different users&#39; wishes (and {\em not\/} the</span>
<span class="hl com">`arbitrary&#39; wishes of the author of the low-level device driver, as is</span>
<span class="hl com">the case in the old scheme). The register $mc_flags$ is used to buffer</span>
<span class="hl com">the information from $media_changed()$ to two separate queues. Other</span>
<span class="hl com">data that is specific to a minor drive, can be accessed through $handle$,</span>
<span class="hl com">which can point to a data structure specific to the low-level driver.</span>
<span class="hl com">The fields $use_count$, $next$, $options$ and $mc_flags$ need not be</span>
<span class="hl com">initialized.</span>
<span class="hl com"></span>
<span class="hl com">The intermediate software layer that \cdromc\ forms will perform some</span>
<span class="hl com">additional bookkeeping. The use count of the device (the number of</span>
<span class="hl com">processes that have the device opened) is registered in $use_count$. The</span>
<span class="hl com">function $cdrom_ioctl()$ will verify the appropriate user-memory regions</span>
<span class="hl com">for read and write, and in case a location on the CD is transferred,</span>
<span class="hl com">it will `sanitize&#39; the format by making requests to the low-level</span>
<span class="hl com">drivers in a standard format, and translating all formats between the</span>
<span class="hl com">user-software and low level drivers. This relieves much of the drivers&#39;</span>
<span class="hl com">memory checking and format checking and translation. Also, the necessary</span>
<span class="hl com">structures will be declared on the program stack.</span>
<span class="hl com"></span>
<span class="hl com">The implementation of the functions should be as defined in the</span>
<span class="hl com">following sections. Two functions {\em must\/} be implemented, namely</span>
<span class="hl com">$open()$ and $release()$. Other functions may be omitted, their</span>
<span class="hl com">corresponding capability flags will be cleared upon registration.</span>
<span class="hl com">Generally, a function returns zero on success and negative on error. A</span>
<span class="hl com">function call should return only after the command has completed, but of</span>
<span class="hl com">course waiting for the device should not use processor time.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ open(struct\ cdrom_device_info * cdi, int\ purpose)$}</span>
<span class="hl com"></span>
<span class="hl com">$Open()$ should try to open the device for a specific $purpose$, which</span>
<span class="hl com">can be either:</span>
<span class="hl com">\begin{itemize}</span>
<span class="hl com">\item[0] Open for reading data, as done by {\tt {mount()}} (2), or the</span>
<span class="hl com">user commands {\tt {dd}} or {\tt {cat}}.  </span>
<span class="hl com">\item[1] Open for $ioctl$ commands, as done by audio-CD playing</span>
<span class="hl com">programs.</span>
<span class="hl com">\end{itemize}</span>
<span class="hl com">Notice that any strategic code (closing tray upon $open()$, etc.)\ is</span>
<span class="hl com">done by the calling routine in \cdromc, so the low-level routine</span>
<span class="hl com">should only be concerned with proper initialization, such as spinning</span>
<span class="hl com">up the disc, etc. % and device-use count</span>
<span class="hl com"></span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Void\ release(struct\ cdrom_device_info * cdi)$}</span>
<span class="hl com"></span>
<span class="hl com"></span>
<span class="hl com">Device-specific actions should be taken such as spinning down the device.</span>
<span class="hl com">However, strategic actions such as ejection of the tray, or unlocking</span>
<span class="hl com">the door, should be left over to the general routine $cdrom_release()$.</span>
<span class="hl com">This is the only function returning type $void$.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ drive_status(struct\ cdrom_device_info * cdi, int\ slot_nr)$}</span>
<span class="hl com">\label{drive status}</span>
<span class="hl com"></span>
<span class="hl com">The function $drive_status$, if implemented, should provide</span>
<span class="hl com">information on the status of the drive (not the status of the disc,</span>
<span class="hl com">which may or may not be in the drive). If the drive is not a changer,</span>
<span class="hl com">$slot_nr$ should be ignored. In \cdromh\ the possibilities are listed: </span>
<span class="hl com">$$</span>
<span class="hl com">\halign{$#$\ \hfil&amp;$/*$ \rm# $*/$\hfil\cr</span>
<span class="hl com">CDS_NO_INFO&amp; no information available\cr</span>
<span class="hl com">CDS_NO_DISC&amp; no disc is inserted, tray is closed\cr</span>
<span class="hl com">CDS_TRAY_OPEN&amp; tray is opened\cr</span>
<span class="hl com">CDS_DRIVE_NOT_READY&amp; something is wrong, tray is moving?\cr</span>
<span class="hl com">CDS_DISC_OK&amp; a disc is loaded and everything is fine\cr</span>
<span class="hl com">}</span>
<span class="hl com">$$</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ media_changed(struct\ cdrom_device_info * cdi, int\ disc_nr)$}</span>
<span class="hl com"></span>
<span class="hl com">This function is very similar to the original function in $struct\ </span>
<span class="hl com">file_operations$. It returns 1 if the medium of the device $cdi\to</span>
<span class="hl com">dev$ has changed since the last call, and 0 otherwise. The parameter</span>
<span class="hl com">$disc_nr$ identifies a specific slot in a juke-box, it should be</span>
<span class="hl com">ignored for single-disc drives.  Note that by `re-routing&#39; this</span>
<span class="hl com">function through $cdrom_media_changed()$, we can implement separate</span>
<span class="hl com">queues for the VFS and a new $ioctl()$ function that can report device</span>
<span class="hl com">changes to software (\eg, an auto-mounting daemon).</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ tray_move(struct\ cdrom_device_info * cdi, int\ position)$}</span>
<span class="hl com"></span>
<span class="hl com">This function, if implemented, should control the tray movement. (No</span>
<span class="hl com">other function should control this.) The parameter $position$ controls</span>
<span class="hl com">the desired direction of movement:</span>
<span class="hl com">\begin{itemize}</span>
<span class="hl com">\item[0] Close tray</span>
<span class="hl com">\item[1] Open tray</span>
<span class="hl com">\end{itemize}</span>
<span class="hl com">This function returns 0 upon success, and a non-zero value upon</span>
<span class="hl com">error. Note that if the tray is already in the desired position, no</span>
<span class="hl com">action need be taken, and the return value should be 0. </span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ lock_door(struct\ cdrom_device_info * cdi, int\ lock)$}</span>
<span class="hl com"></span>
<span class="hl com">This function (and no other code) controls locking of the door, if the</span>
<span class="hl com">drive allows this. The value of $lock$ controls the desired locking</span>
<span class="hl com">state:</span>
<span class="hl com">\begin{itemize}</span>
<span class="hl com">\item[0] Unlock door, manual opening is allowed</span>
<span class="hl com">\item[1] Lock door, tray cannot be ejected manually</span>
<span class="hl com">\end{itemize}</span>
<span class="hl com">This function returns 0 upon success, and a non-zero value upon</span>
<span class="hl com">error. Note that if the door is already in the requested state, no</span>
<span class="hl com">action need be taken, and the return value should be 0. </span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ select_speed(struct\ cdrom_device_info * cdi, int\ speed)$}</span>
<span class="hl com"></span>
<span class="hl com">Some \cdrom\ drives are capable of changing their head-speed. There</span>
<span class="hl com">are several reasons for changing the speed of a \cdrom\ drive. Badly</span>
<span class="hl com">pressed \cdrom s may benefit from less-than-maximum head rate. Modern</span>
<span class="hl com">\cdrom\ drives can obtain very high head rates (up to $24\times$ is</span>
<span class="hl com">common).  It has been reported that these drives can make reading</span>
<span class="hl com">errors at these high speeds, reducing the speed can prevent data loss</span>
<span class="hl com">in these circumstances.  Finally, some of these drives can</span>
<span class="hl com">make an annoyingly loud noise, which a lower speed may reduce. %Finally,</span>
<span class="hl com">%although the audio-low-pass filters probably aren&#39;t designed for it,</span>
<span class="hl com">%more than real-time playback of audio might be used for high-speed</span>
<span class="hl com">%copying of audio tracks.</span>
<span class="hl com"></span>
<span class="hl com">This function specifies the speed at which data is read or audio is</span>
<span class="hl com">played back. The value of $speed$ specifies the head-speed of the</span>
<span class="hl com">drive, measured in units of standard cdrom speed (176\,kB/sec raw data</span>
<span class="hl com">or 150\,kB/sec file system data). So to request that a \cdrom\ drive</span>
<span class="hl com">operate at 300\,kB/sec you would call the CDROM_SELECT_SPEED $ioctl$</span>
<span class="hl com">with $speed=2$. The special value `0&#39; means `auto-selection&#39;, \ie,</span>
<span class="hl com">maximum data-rate or real-time audio rate. If the drive doesn&#39;t have</span>
<span class="hl com">this `auto-selection&#39; capability, the decision should be made on the</span>
<span class="hl com">current disc loaded and the return value should be positive. A negative</span>
<span class="hl com">return value indicates an error.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ select_disc(struct\ cdrom_device_info * cdi, int\ number)$}</span>
<span class="hl com"></span>
<span class="hl com">If the drive can store multiple discs (a juke-box) this function</span>
<span class="hl com">will perform disc selection. It should return the number of the</span>
<span class="hl com">selected disc on success, a negative value on error. Currently, only</span>
<span class="hl com">the ide-cd driver supports this functionality.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ get_last_session(struct\ cdrom_device_info * cdi, struct\</span>
<span class="hl com">  cdrom_multisession * ms_info)$}</span>
<span class="hl com"></span>
<span class="hl com">This function should implement the old corresponding $ioctl()$. For</span>
<span class="hl com">device $cdi\to dev$, the start of the last session of the current disc</span>
<span class="hl com">should be returned in the pointer argument $ms_info$. Note that</span>
<span class="hl com">routines in \cdromc\ have sanitized this argument: its requested</span>
<span class="hl com">format will {\em always\/} be of the type $CDROM_LBA$ (linear block</span>
<span class="hl com">addressing mode), whatever the calling software requested. But</span>
<span class="hl com">sanitization goes even further: the low-level implementation may</span>
<span class="hl com">return the requested information in $CDROM_MSF$ format if it wishes so</span>
<span class="hl com">(setting the $ms_info\rightarrow addr_format$ field appropriately, of</span>
<span class="hl com">course) and the routines in \cdromc\ will make the transformation if</span>
<span class="hl com">necessary. The return value is 0 upon success.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ get_mcn(struct\ cdrom_device_info * cdi, struct\</span>
<span class="hl com">  cdrom_mcn * mcn)$}</span>
<span class="hl com"></span>
<span class="hl com">Some discs carry a `Media Catalog Number&#39; (MCN), also called</span>
<span class="hl com">`Universal Product Code&#39; (UPC). This number should reflect the number</span>
<span class="hl com">that is generally found in the bar-code on the product. Unfortunately,</span>
<span class="hl com">the few discs that carry such a number on the disc don&#39;t even use the</span>
<span class="hl com">same format. The return argument to this function is a pointer to a</span>
<span class="hl com">pre-declared memory region of type $struct\ cdrom_mcn$. The MCN is</span>
<span class="hl com">expected as a 13-character string, terminated by a null-character.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ reset(struct\ cdrom_device_info * cdi)$}</span>
<span class="hl com"></span>
<span class="hl com">This call should perform a hard-reset on the drive (although in</span>
<span class="hl com">circumstances that a hard-reset is necessary, a drive may very well not</span>
<span class="hl com">listen to commands anymore). Preferably, control is returned to the</span>
<span class="hl com">caller only after the drive has finished resetting. If the drive is no</span>
<span class="hl com">longer listening, it may be wise for the underlying low-level cdrom</span>
<span class="hl com">driver to time out.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ audio_ioctl(struct\ cdrom_device_info * cdi, unsigned\</span>
<span class="hl com">  int\ cmd, void * arg)$}</span>
<span class="hl com"></span>
<span class="hl com">Some of the \cdrom-$ioctl$s defined in \cdromh\ can be</span>
<span class="hl com">implemented by the routines described above, and hence the function</span>
<span class="hl com">$cdrom_ioctl$ will use those. However, most $ioctl$s deal with</span>
<span class="hl com">audio-control. We have decided to leave these to be accessed through a</span>
<span class="hl com">single function, repeating the arguments $cmd$ and $arg$. Note that</span>
<span class="hl com">the latter is of type $void*{}$, rather than $unsigned\ long\</span>
<span class="hl com">int$. The routine $cdrom_ioctl()$ does do some useful things,</span>
<span class="hl com">though. It sanitizes the address format type to $CDROM_MSF$ (Minutes,</span>
<span class="hl com">Seconds, Frames) for all audio calls. It also verifies the memory</span>
<span class="hl com">location of $arg$, and reserves stack-memory for the argument. This</span>
<span class="hl com">makes implementation of the $audio_ioctl()$ much simpler than in the</span>
<span class="hl com">old driver scheme. For example, you may look up the function</span>
<span class="hl com">$cm206_audio_ioctl()$ in {\tt {cm206.c}} that should be updated with</span>
<span class="hl com">this documentation. </span>
<span class="hl com"></span>
<span class="hl com">An unimplemented ioctl should return $-ENOSYS$, but a harmless request</span>
<span class="hl com">(\eg, $CDROMSTART$) may be ignored by returning 0 (success). Other</span>
<span class="hl com">errors should be according to the standards, whatever they are. When</span>
<span class="hl com">an error is returned by the low-level driver, the \UCD\ tries whenever</span>
<span class="hl com">possible to return the error code to the calling program. (We may decide</span>
<span class="hl com">to sanitize the return value in $cdrom_ioctl()$ though, in order to</span>
<span class="hl com">guarantee a uniform interface to the audio-player software.)</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ dev_ioctl(struct\ cdrom_device_info * cdi, unsigned\ int\</span>
<span class="hl com">  cmd, unsigned\ long\ arg)$}</span>
<span class="hl com"></span>
<span class="hl com">Some $ioctl$s seem to be specific to certain \cdrom\ drives. That is,</span>
<span class="hl com">they are introduced to service some capabilities of certain drives. In</span>
<span class="hl com">fact, there are 6 different $ioctl$s for reading data, either in some</span>
<span class="hl com">particular kind of format, or audio data. Not many drives support</span>
<span class="hl com">reading audio tracks as data, I believe this is because of protection</span>
<span class="hl com">of copyrights of artists. Moreover, I think that if audio-tracks are</span>
<span class="hl com">supported, it should be done through the VFS and not via $ioctl$s. A</span>
<span class="hl com">problem here could be the fact that audio-frames are 2352 bytes long,</span>
<span class="hl com">so either the audio-file-system should ask for 75264 bytes at once</span>
<span class="hl com">(the least common multiple of 512 and 2352), or the drivers should</span>
<span class="hl com">bend their backs to cope with this incoherence (to which I would be</span>
<span class="hl com">opposed).  Furthermore, it is very difficult for the hardware to find</span>
<span class="hl com">the exact frame boundaries, since there are no synchronization headers</span>
<span class="hl com">in audio frames.  Once these issues are resolved, this code should be</span>
<span class="hl com">standardized in \cdromc.</span>
<span class="hl com"></span>
<span class="hl com">Because there are so many $ioctl$s that seem to be introduced to</span>
<span class="hl com">satisfy certain drivers,\footnote{Is there software around that</span>
<span class="hl com">  actually uses these? I&#39;d be interested!} any `non-standard&#39; $ioctl$s</span>
<span class="hl com">are routed through the call $dev_ioctl()$. In principle, `private&#39;</span>
<span class="hl com">$ioctl$s should be numbered after the device&#39;s major number, and not</span>
<span class="hl com">the general \cdrom\ $ioctl$ number, {\tt {0x53}}. Currently the</span>
<span class="hl com">non-supported $ioctl$s are: {\it CDROMREADMODE1, CDROMREADMODE2,</span>
<span class="hl com">  CDROMREADAUDIO, CDROMREADRAW, CDROMREADCOOKED, CDROMSEEK,</span>
<span class="hl com">  CDROMPLAY\-BLK and CDROM\-READALL}.</span>
<span class="hl com"></span>
<span class="hl com"></span>
<span class="hl com">\subsection{\cdrom\ capabilities}</span>
<span class="hl com">\label{capability}</span>
<span class="hl com"></span>
<span class="hl com">Instead of just implementing some $ioctl$ calls, the interface in</span>
<span class="hl com">\cdromc\ supplies the possibility to indicate the {\em capabilities\/}</span>
<span class="hl com">of a \cdrom\ drive. This can be done by ORing any number of</span>
<span class="hl com">capability-constants that are defined in \cdromh\ at the registration</span>
<span class="hl com">phase. Currently, the capabilities are any of:</span>
<span class="hl com">$$</span>
<span class="hl com">\halign{$#$\ \hfil&amp;$/*$ \rm# $*/$\hfil\cr</span>
<span class="hl com">CDC_CLOSE_TRAY&amp; can close tray by software control\cr</span>
<span class="hl com">CDC_OPEN_TRAY&amp; can open tray\cr</span>
<span class="hl com">CDC_LOCK&amp; can lock and unlock the door\cr</span>
<span class="hl com">CDC_SELECT_SPEED&amp; can select speed, in units of $\sim$150\,kB/s\cr</span>
<span class="hl com">CDC_SELECT_DISC&amp; drive is juke-box\cr</span>
<span class="hl com">CDC_MULTI_SESSION&amp; can read sessions $&gt;\rm1$\cr</span>
<span class="hl com">CDC_MCN&amp; can read Media Catalog Number\cr</span>
<span class="hl com">CDC_MEDIA_CHANGED&amp; can report if disc has changed\cr</span>
<span class="hl com">CDC_PLAY_AUDIO&amp; can perform audio-functions (play, pause, etc)\cr</span>
<span class="hl com">CDC_RESET&amp; hard reset device\cr</span>
<span class="hl com">CDC_IOCTLS&amp; driver has non-standard ioctls\cr</span>
<span class="hl com">CDC_DRIVE_STATUS&amp; driver implements drive status\cr</span>
<span class="hl com">}</span>
<span class="hl com">$$</span>
<span class="hl com">The capability flag is declared $const$, to prevent drivers from</span>
<span class="hl com">accidentally tampering with the contents. The capability fags actually</span>
<span class="hl com">inform \cdromc\ of what the driver can do. If the drive found</span>
<span class="hl com">by the driver does not have the capability, is can be masked out by</span>
<span class="hl com">the $cdrom_device_info$ variable $mask$. For instance, the SCSI \cdrom\</span>
<span class="hl com">driver has implemented the code for loading and ejecting \cdrom&#39;s, and</span>
<span class="hl com">hence its corresponding flags in $capability$ will be set. But a SCSI</span>
<span class="hl com">\cdrom\ drive might be a caddy system, which can&#39;t load the tray, and</span>
<span class="hl com">hence for this drive the $cdrom_device_info$ struct will have set</span>
<span class="hl com">the $CDC_CLOSE_TRAY$ bit in $mask$.</span>
<span class="hl com"></span>
<span class="hl com">In the file \cdromc\ you will encounter many constructions of the type</span>
<span class="hl com">$$\it</span>
<span class="hl com">if\ (cdo\rightarrow capability \mathrel\&amp; \mathord{\sim} cdi\rightarrow mask </span>
<span class="hl com">   \mathrel{\&amp;} CDC_&lt;capability&gt;) \ldots</span>
<span class="hl com">$$</span>
<span class="hl com">There is no $ioctl$ to set the mask\dots The reason is that</span>
<span class="hl com">I think it is better to control the {\em behavior\/} rather than the</span>
<span class="hl com">{\em capabilities}.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{Options}</span>
<span class="hl com"></span>
<span class="hl com">A final flag register controls the {\em behavior\/} of the \cdrom\</span>
<span class="hl com">drives, in order to satisfy different users&#39; wishes, hopefully</span>
<span class="hl com">independently of the ideas of the respective author who happened to</span>
<span class="hl com">have made the drive&#39;s support available to the \linux\ community. The</span>
<span class="hl com">current behavior options are:</span>
<span class="hl com">$$</span>
<span class="hl com">\halign{$#$\ \hfil&amp;$/*$ \rm# $*/$\hfil\cr</span>
<span class="hl com">CDO_AUTO_CLOSE&amp; try to close tray upon device $open()$\cr</span>
<span class="hl com">CDO_AUTO_EJECT&amp; try to open tray on last device $close()$\cr</span>
<span class="hl com">CDO_USE_FFLAGS&amp; use $file_pointer\rightarrow f_flags$ to indicate</span>
<span class="hl com"> purpose for $open()$\cr</span>
<span class="hl com">CDO_LOCK&amp; try to lock door if device is opened\cr</span>
<span class="hl com">CDO_CHECK_TYPE&amp; ensure disc type is data if opened for data\cr</span>
<span class="hl com">}</span>
<span class="hl com">$$</span>
<span class="hl com"></span>
<span class="hl com">The initial value of this register is $CDO_AUTO_CLOSE \mathrel|</span>
<span class="hl com">CDO_USE_FFLAGS \mathrel| CDO_LOCK$, reflecting my own view on user</span>
<span class="hl com">interface and software standards. Before you protest, there are two</span>
<span class="hl com">new $ioctl$s implemented in \cdromc, that allow you to control the</span>
<span class="hl com">behavior by software. These are:</span>
<span class="hl com">$$</span>
<span class="hl com">\halign{$#$\ \hfil&amp;$/*$ \rm# $*/$\hfil\cr</span>
<span class="hl com">CDROM_SET_OPTIONS&amp; set options specified in $(int)\ arg$\cr</span>
<span class="hl com">CDROM_CLEAR_OPTIONS&amp; clear options specified in $(int)\ arg$\cr</span>
<span class="hl com">}</span>
<span class="hl com">$$</span>
<span class="hl com">One option needs some more explanation: $CDO_USE_FFLAGS$. In the next</span>
<span class="hl com">newsection we explain what the need for this option is.</span>
<span class="hl com"></span>
<span class="hl com">A software package {\tt setcd}, available from the Debian distribution</span>
<span class="hl com">and {\tt sunsite.unc.edu}, allows user level control of these flags. </span>
<span class="hl com"></span>
<span class="hl com">\newsection{The need to know the purpose of opening the \cdrom\ device}</span>
<span class="hl com"></span>
<span class="hl com">Traditionally, Unix devices can be used in two different `modes&#39;,</span>
<span class="hl com">either by reading/writing to the device file, or by issuing</span>
<span class="hl com">controlling commands to the device, by the device&#39;s $ioctl()$</span>
<span class="hl com">call. The problem with \cdrom\ drives, is that they can be used for</span>
<span class="hl com">two entirely different purposes. One is to mount removable</span>
<span class="hl com">file systems, \cdrom s, the other is to play audio CD&#39;s. Audio commands</span>
<span class="hl com">are implemented entirely through $ioctl$s, presumably because the</span>
<span class="hl com">first implementation (SUN?) has been such. In principle there is</span>
<span class="hl com">nothing wrong with this, but a good control of the `CD player&#39; demands</span>
<span class="hl com">that the device can {\em always\/} be opened in order to give the</span>
<span class="hl com">$ioctl$ commands, regardless of the state the drive is in. </span>
<span class="hl com"></span>
<span class="hl com">On the other hand, when used as a removable-media disc drive (what the</span>
<span class="hl com">original purpose of \cdrom s is) we would like to make sure that the</span>
<span class="hl com">disc drive is ready for operation upon opening the device. In the old</span>
<span class="hl com">scheme, some \cdrom\ drivers don&#39;t do any integrity checking, resulting</span>
<span class="hl com">in a number of i/o errors reported by the VFS to the kernel when an</span>
<span class="hl com">attempt for mounting a \cdrom\ on an empty drive occurs. This is not a</span>
<span class="hl com">particularly elegant way to find out that there is no \cdrom\ inserted;</span>
<span class="hl com">it more-or-less looks like the old IBM-PC trying to read an empty floppy</span>
<span class="hl com">drive for a couple of seconds, after which the system complains it</span>
<span class="hl com">can&#39;t read from it. Nowadays we can {\em sense\/} the existence of a</span>
<span class="hl com">removable medium in a drive, and we believe we should exploit that</span>
<span class="hl com">fact. An integrity check on opening of the device, that verifies the</span>
<span class="hl com">availability of a \cdrom\ and its correct type (data), would be</span>
<span class="hl com">desirable.</span>
<span class="hl com"></span>
<span class="hl com">These two ways of using a \cdrom\ drive, principally for data and</span>
<span class="hl com">secondarily for playing audio discs, have different demands for the</span>
<span class="hl com">behavior of the $open()$ call. Audio use simply wants to open the</span>
<span class="hl com">device in order to get a file handle which is needed for issuing</span>
<span class="hl com">$ioctl$ commands, while data use wants to open for correct and</span>
<span class="hl com">reliable data transfer. The only way user programs can indicate what</span>
<span class="hl com">their {\em purpose\/} of opening the device is, is through the $flags$</span>
<span class="hl com">parameter (see {\tt {open(2)}}). For \cdrom\ devices, these flags aren&#39;t</span>
<span class="hl com">implemented (some drivers implement checking for write-related flags,</span>
<span class="hl com">but this is not strictly necessary if the device file has correct</span>
<span class="hl com">permission flags). Most option flags simply don&#39;t make sense to</span>
<span class="hl com">\cdrom\ devices: $O_CREAT$, $O_NOCTTY$, $O_TRUNC$, $O_APPEND$, and</span>
<span class="hl com">$O_SYNC$ have no meaning to a \cdrom. </span>
<span class="hl com"></span>
<span class="hl com">We therefore propose to use the flag $O_NONBLOCK$ to indicate</span>
<span class="hl com">that the device is opened just for issuing $ioctl$</span>
<span class="hl com">commands. Strictly, the meaning of $O_NONBLOCK$ is that opening and</span>
<span class="hl com">subsequent calls to the device don&#39;t cause the calling process to</span>
<span class="hl com">wait. We could interpret this as ``don&#39;t wait until someone has</span>
<span class="hl com">inserted some valid data-\cdrom.&#39;&#39; Thus, our proposal of the</span>
<span class="hl com">implementation for the $open()$ call for \cdrom s is:</span>
<span class="hl com">\begin{itemize}</span>
<span class="hl com">\item If no other flags are set than $O_RDONLY$, the device is opened</span>
<span class="hl com">for data transfer, and the return value will be 0 only upon successful</span>
<span class="hl com">initialization of the transfer. The call may even induce some actions</span>
<span class="hl com">on the \cdrom, such as closing the tray.  </span>
<span class="hl com">\item If the option flag $O_NONBLOCK$ is set, opening will always be</span>
<span class="hl com">successful, unless the whole device doesn&#39;t exist. The drive will take</span>
<span class="hl com">no actions whatsoever. </span>
<span class="hl com">\end{itemize}</span>
<span class="hl com"></span>
<span class="hl com">\subsection{And what about standards?}</span>
<span class="hl com"></span>
<span class="hl com">You might hesitate to accept this proposal as it comes from the</span>
<span class="hl com">\linux\ community, and not from some standardizing institute. What</span>
<span class="hl com">about SUN, SGI, HP and all those other Unix and hardware vendors?</span>
<span class="hl com">Well, these companies are in the lucky position that they generally</span>
<span class="hl com">control both the hardware and software of their supported products,</span>
<span class="hl com">and are large enough to set their own standard. They do not have to</span>
<span class="hl com">deal with a dozen or more different, competing hardware</span>
<span class="hl com">configurations.\footnote{Incidentally, I think that SUN&#39;s approach to</span>
<span class="hl com">mounting \cdrom s is very good in origin: under Solaris a</span>
<span class="hl com">volume-daemon automatically mounts a newly inserted \cdrom\ under {\tt</span>
<span class="hl com">{/cdrom/$&lt;volume-name&gt;$/}}. In my opinion they should have pushed this</span>
<span class="hl com">further and have {\em every\/} \cdrom\ on the local area network be</span>
<span class="hl com">mounted at the similar location, \ie, no matter in which particular</span>
<span class="hl com">machine you insert a \cdrom, it will always appear at the same</span>
<span class="hl com">position in the directory tree, on every system. When I wanted to</span>
<span class="hl com">implement such a user-program for \linux, I came across the</span>
<span class="hl com">differences in behavior of the various drivers, and the need for an</span>
<span class="hl com">$ioctl$ informing about media changes.}</span>
<span class="hl com"></span>
<span class="hl com">We believe that using $O_NONBLOCK$ to indicate that a device is being opened</span>
<span class="hl com">for $ioctl$ commands only can be easily introduced in the \linux\</span>
<span class="hl com">community. All the CD-player authors will have to be informed, we can</span>
<span class="hl com">even send in our own patches to the programs. The use of $O_NONBLOCK$</span>
<span class="hl com">has most likely no influence on the behavior of the CD-players on</span>
<span class="hl com">other operating systems than \linux. Finally, a user can always revert</span>
<span class="hl com">to old behavior by a call to $ioctl(file_descriptor, CDROM_CLEAR_OPTIONS,</span>
<span class="hl com">CDO_USE_FFLAGS)$. </span>
<span class="hl com"></span>
<span class="hl com">\subsection{The preferred strategy of $open()$}</span>
<span class="hl com"></span>
<span class="hl com">The routines in \cdromc\ are designed in such a way that run-time</span>
<span class="hl com">configuration of the behavior of \cdrom\ devices (of {\em any\/} type)</span>
<span class="hl com">can be carried out, by the $CDROM_SET/CLEAR_OPTIONS$ $ioctls$. Thus, various</span>
<span class="hl com">modes of operation can be set:</span>
<span class="hl com">\begin{description}</span>
<span class="hl com">\item[$CDO_AUTO_CLOSE \mathrel| CDO_USE_FFLAGS \mathrel| CDO_LOCK$] This</span>
<span class="hl com">is the default setting. (With $CDO_CHECK_TYPE$ it will be better, in the</span>
<span class="hl com">future.) If the device is not yet opened by any other process, and if</span>
<span class="hl com">the device is being opened for data ($O_NONBLOCK$ is not set) and the</span>
<span class="hl com">tray is found to be open, an attempt to close the tray is made. Then,</span>
<span class="hl com">it is verified that a disc is in the drive and, if $CDO_CHECK_TYPE$ is</span>
<span class="hl com">set, that it contains tracks of type `data mode 1.&#39; Only if all tests</span>
<span class="hl com">are passed is the return value zero. The door is locked to prevent file</span>
<span class="hl com">system corruption. If the drive is opened for audio ($O_NONBLOCK$ is</span>
<span class="hl com">set), no actions are taken and a value of 0 will be returned. </span>
<span class="hl com">\item[$CDO_AUTO_CLOSE \mathrel| CDO_AUTO_EJECT \mathrel| CDO_LOCK$] This</span>
<span class="hl com">mimics the behavior of the current sbpcd-driver. The option flags are</span>
<span class="hl com">ignored, the tray is closed on the first open, if necessary. Similarly,</span>
<span class="hl com">the tray is opened on the last release, \ie, if a \cdrom\ is unmounted,</span>
<span class="hl com">it is automatically ejected, such that the user can replace it.</span>
<span class="hl com">\end{description} </span>
<span class="hl com">We hope that these option can convince everybody (both driver</span>
<span class="hl com">maintainers and user program developers) to adopt the new \cdrom\</span>
<span class="hl com">driver scheme and option flag interpretation.</span>
<span class="hl com"></span>
<span class="hl com">\newsection{Description of routines in \cdromc}</span>
<span class="hl com"></span>
<span class="hl com">Only a few routines in \cdromc\ are exported to the drivers. In this</span>
<span class="hl com">new section we will discuss these, as well as the functions that `take</span>
<span class="hl com">over&#39; the \cdrom\ interface to the kernel. The header file belonging</span>
<span class="hl com">to \cdromc\ is called \cdromh. Formerly, some of the contents of this</span>
<span class="hl com">file were placed in the file {\tt {ucdrom.h}}, but this file has now been</span>
<span class="hl com">merged back into \cdromh.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Struct\ file_operations\ cdrom_fops$}</span>
<span class="hl com"></span>
<span class="hl com">The contents of this structure were described in section~\ref{cdrom.c}.</span>
<span class="hl com">A pointer to this structure is assigned to the $fops$ field</span>
<span class="hl com">of the $struct gendisk$.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ register_cdrom( struct\ cdrom_device_info\ * cdi)$}</span>
<span class="hl com"></span>
<span class="hl com">This function is used in about the same way one registers $cdrom_fops$</span>
<span class="hl com">with the kernel, the device operations and information structures,</span>
<span class="hl com">as described in section~\ref{cdrom.c}, should be registered with the</span>
<span class="hl com">\UCD:</span>
<span class="hl com">$$</span>
<span class="hl com">register_cdrom(\&amp;&lt;device&gt;_info));</span>
<span class="hl com">$$</span>
<span class="hl com">This function returns zero upon success, and non-zero upon</span>
<span class="hl com">failure. The structure $&lt;device&gt;_info$ should have a pointer to the</span>
<span class="hl com">driver&#39;s $&lt;device&gt;_dops$, as in </span>
<span class="hl com">$$</span>
<span class="hl com">\vbox{\halign{&amp;$#$\hfil\cr</span>
<span class="hl com">struct\ &amp;cdrom_device_info\ &lt;device&gt;_info = \{\cr</span>
<span class="hl com">&amp; &lt;device&gt;_dops;\cr</span>
<span class="hl com">&amp;\ldots\cr</span>
<span class="hl com">\}\cr</span>
<span class="hl com">}}$$</span>
<span class="hl com">Note that a driver must have one static structure, $&lt;device&gt;_dops$, while</span>
<span class="hl com">it may have as many structures $&lt;device&gt;_info$ as there are minor devices</span>
<span class="hl com">active. $Register_cdrom()$ builds a linked list from these. </span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Void\ unregister_cdrom(struct\ cdrom_device_info * cdi)$}</span>
<span class="hl com"></span>
<span class="hl com">Unregistering device $cdi$ with minor number $MINOR(cdi\to dev)$ removes</span>
<span class="hl com">the minor device from the list. If it was the last registered minor for</span>
<span class="hl com">the low-level driver, this disconnects the registered device-operation</span>
<span class="hl com">routines from the \cdrom\ interface. This function returns zero upon</span>
<span class="hl com">success, and non-zero upon failure.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ cdrom_open(struct\ inode * ip, struct\ file * fp)$}</span>
<span class="hl com"></span>
<span class="hl com">This function is not called directly by the low-level drivers, it is</span>
<span class="hl com">listed in the standard $cdrom_fops$. If the VFS opens a file, this</span>
<span class="hl com">function becomes active. A strategy is implemented in this routine,</span>
<span class="hl com">taking care of all capabilities and options that are set in the</span>
<span class="hl com">$cdrom_device_ops$ connected to the device. Then, the program flow is</span>
<span class="hl com">transferred to the device_dependent $open()$ call.</span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Void\ cdrom_release(struct\ inode *ip, struct\ file</span>
<span class="hl com">*fp)$}</span>
<span class="hl com"></span>
<span class="hl com">This function implements the reverse-logic of $cdrom_open()$, and then</span>
<span class="hl com">calls the device-dependent $release()$ routine. When the use-count has</span>
<span class="hl com">reached 0, the allocated buffers are flushed by calls to $sync_dev(dev)$</span>
<span class="hl com">and $invalidate_buffers(dev)$.</span>
<span class="hl com"></span>
<span class="hl com"></span>
<span class="hl com">\subsection{$Int\ cdrom_ioctl(struct\ inode *ip, struct\ file *fp,</span>
<span class="hl com">unsigned\ int\ cmd, unsigned\ long\ arg)$}</span>
<span class="hl com">\label{cdrom-ioctl}</span>
<span class="hl com"></span>
<span class="hl com">This function handles all the standard $ioctl$ requests for \cdrom\</span>
<span class="hl com">devices in a uniform way. The different calls fall into three</span>
<span class="hl com">categories: $ioctl$s that can be directly implemented by device</span>
<span class="hl com">operations, ones that are routed through the call $audio_ioctl()$, and</span>
<span class="hl com">the remaining ones, that are presumable device-dependent. Generally, a</span>
<span class="hl com">negative return value indicates an error.</span>
<span class="hl com"></span>
<span class="hl com">\subsubsection{Directly implemented $ioctl$s}</span>
<span class="hl com">\label{ioctl-direct}</span>
<span class="hl com"></span>
<span class="hl com">The following `old&#39; \cdrom-$ioctl$s are implemented by directly</span>
<span class="hl com">calling device-operations in $cdrom_device_ops$, if implemented and</span>
<span class="hl com">not masked:</span>
<span class="hl com">\begin{description}</span>
<span class="hl com">\item[CDROMMULTISESSION] Requests the last session on a \cdrom.</span>
<span class="hl com">\item[CDROMEJECT] Open tray. </span>
<span class="hl com">\item[CDROMCLOSETRAY] Close tray.</span>
<span class="hl com">\item[CDROMEJECT_SW] If $arg\not=0$, set behavior to auto-close (close</span>
<span class="hl com">tray on first open) and auto-eject (eject on last release), otherwise</span>
<span class="hl com">set behavior to non-moving on $open()$ and $release()$ calls.</span>
<span class="hl com">\item[CDROM_GET_MCN] Get the Media Catalog Number from a CD.</span>
<span class="hl com">\end{description}</span>
<span class="hl com"></span>
<span class="hl com">\subsubsection{$Ioctl$s routed through $audio_ioctl()$}</span>
<span class="hl com">\label{ioctl-audio}</span>
<span class="hl com"></span>
<span class="hl com">The following set of $ioctl$s are all implemented through a call to</span>
<span class="hl com">the $cdrom_fops$ function $audio_ioctl()$. Memory checks and</span>
<span class="hl com">allocation are performed in $cdrom_ioctl()$, and also sanitization of</span>
<span class="hl com">address format ($CDROM_LBA$/$CDROM_MSF$) is done.</span>
<span class="hl com">\begin{description}</span>
<span class="hl com">\item[CDROMSUBCHNL] Get sub-channel data in argument $arg$ of type $struct\</span>
<span class="hl com">cdrom_subchnl *{}$.</span>
<span class="hl com">\item[CDROMREADTOCHDR] Read Table of Contents header, in $arg$ of type</span>
<span class="hl com">$struct\ cdrom_tochdr *{}$. </span>
<span class="hl com">\item[CDROMREADTOCENTRY] Read a Table of Contents entry in $arg$ and</span>
<span class="hl com">specified by $arg$ of type $struct\ cdrom_tocentry *{}$.</span>
<span class="hl com">\item[CDROMPLAYMSF] Play audio fragment specified in Minute, Second,</span>
<span class="hl com">Frame format, delimited by $arg$ of type $struct\ cdrom_msf *{}$.</span>
<span class="hl com">\item[CDROMPLAYTRKIND] Play audio fragment in track-index format</span>
<span class="hl com">delimited by $arg$ of type $struct\ \penalty-1000 cdrom_ti *{}$.</span>
<span class="hl com">\item[CDROMVOLCTRL] Set volume specified by $arg$ of type $struct\</span>
<span class="hl com">cdrom_volctrl *{}$.</span>
<span class="hl com">\item[CDROMVOLREAD] Read volume into by $arg$ of type $struct\</span>
<span class="hl com">cdrom_volctrl *{}$.</span>
<span class="hl com">\item[CDROMSTART] Spin up disc.</span>
<span class="hl com">\item[CDROMSTOP] Stop playback of audio fragment.</span>
<span class="hl com">\item[CDROMPAUSE] Pause playback of audio fragment.</span>
<span class="hl com">\item[CDROMRESUME] Resume playing.</span>
<span class="hl com">\end{description}</span>
<span class="hl com"></span>
<span class="hl com">\subsubsection{New $ioctl$s in \cdromc}</span>
<span class="hl com"></span>
<span class="hl com">The following $ioctl$s have been introduced to allow user programs to</span>
<span class="hl com">control the behavior of individual \cdrom\ devices. New $ioctl$</span>
<span class="hl com">commands can be identified by the underscores in their names.</span>
<span class="hl com">\begin{description}</span>
<span class="hl com">\item[CDROM_SET_OPTIONS] Set options specified by $arg$. Returns the</span>
<span class="hl com">option flag register after modification. Use  $arg = \rm0$ for reading</span>
<span class="hl com">the current flags.</span>
<span class="hl com">\item[CDROM_CLEAR_OPTIONS] Clear options specified by $arg$. Returns</span>
<span class="hl com">  the option flag register after modification.</span>
<span class="hl com">\item[CDROM_SELECT_SPEED] Select head-rate speed of disc specified as</span>
<span class="hl com">  by $arg$ in units of standard cdrom speed (176\,kB/sec raw data or</span>
<span class="hl com">  150\,kB/sec file system data). The value 0 means `auto-select&#39;, \ie,</span>
<span class="hl com">  play audio discs at real time and data discs at maximum speed. The value</span>
<span class="hl com">  $arg$ is checked against the maximum head rate of the drive found in the</span>
<span class="hl com">  $cdrom_dops$.</span>
<span class="hl com">\item[CDROM_SELECT_DISC] Select disc numbered $arg$ from a juke-box.</span>
<span class="hl com">  First disc is numbered 0. The number $arg$ is checked against the</span>
<span class="hl com">  maximum number of discs in the juke-box found in the $cdrom_dops$.</span>
<span class="hl com">\item[CDROM_MEDIA_CHANGED] Returns 1 if a disc has been changed since</span>
<span class="hl com">  the last call. Note that calls to $cdrom_media_changed$ by the VFS</span>
<span class="hl com">  are treated by an independent queue, so both mechanisms will detect</span>
<span class="hl com">  a media change once. For juke-boxes, an extra argument $arg$</span>
<span class="hl com">  specifies the slot for which the information is given. The special</span>
<span class="hl com">  value $CDSL_CURRENT$ requests that information about the currently</span>
<span class="hl com">  selected slot be returned.</span>
<span class="hl com">\item[CDROM_DRIVE_STATUS] Returns the status of the drive by a call to</span>
<span class="hl com">  $drive_status()$. Return values are defined in section~\ref{drive</span>
<span class="hl com">   status}. Note that this call doesn&#39;t return information on the</span>
<span class="hl com">  current playing activity of the drive; this can be polled through an</span>
<span class="hl com">  $ioctl$ call to $CDROMSUBCHNL$. For juke-boxes, an extra argument</span>
<span class="hl com">  $arg$ specifies the slot for which (possibly limited) information is</span>
<span class="hl com">  given. The special value $CDSL_CURRENT$ requests that information</span>
<span class="hl com">  about the currently selected slot be returned.</span>
<span class="hl com">\item[CDROM_DISC_STATUS] Returns the type of the disc currently in the</span>
<span class="hl com">  drive.  It should be viewed as a complement to $CDROM_DRIVE_STATUS$.</span>
<span class="hl com">  This $ioctl$ can provide \emph {some} information about the current</span>
<span class="hl com">  disc that is inserted in the drive.  This functionality used to be</span>
<span class="hl com">  implemented in the low level drivers, but is now carried out</span>
<span class="hl com">  entirely in \UCD.</span>
<span class="hl com">  </span>
<span class="hl com">  The history of development of the CD&#39;s use as a carrier medium for</span>
<span class="hl com">  various digital information has lead to many different disc types.</span>
<span class="hl com">  This $ioctl$ is useful only in the case that CDs have \emph {only</span>
<span class="hl com">    one} type of data on them.  While this is often the case, it is</span>
<span class="hl com">  also very common for CDs to have some tracks with data, and some</span>
<span class="hl com">  tracks with audio.  Because this is an existing interface, rather</span>
<span class="hl com">  than fixing this interface by changing the assumptions it was made</span>
<span class="hl com">  under, thereby breaking all user applications that use this</span>
<span class="hl com">  function, the \UCD\ implements this $ioctl$ as follows: If the CD in</span>
<span class="hl com">  question has audio tracks on it, and it has absolutely no CD-I, XA,</span>
<span class="hl com">  or data tracks on it, it will be reported as $CDS_AUDIO$.  If it has</span>
<span class="hl com">  both audio and data tracks, it will return $CDS_MIXED$.  If there</span>
<span class="hl com">  are no audio tracks on the disc, and if the CD in question has any</span>
<span class="hl com">  CD-I tracks on it, it will be reported as $CDS_XA_2_2$.  Failing</span>
<span class="hl com">  that, if the CD in question has any XA tracks on it, it will be</span>
<span class="hl com">  reported as $CDS_XA_2_1$.  Finally, if the CD in question has any</span>
<span class="hl com">  data tracks on it, it will be reported as a data CD ($CDS_DATA_1$).</span>
<span class="hl com"></span>
<span class="hl com">  This $ioctl$ can return:</span>
<span class="hl com">  $$</span>
<span class="hl com">  \halign{$#$\ \hfil&amp;$/*$ \rm# $*/$\hfil\cr</span>
<span class="hl com">    CDS_NO_INFO&amp; no information available\cr</span>
<span class="hl com">    CDS_NO_DISC&amp; no disc is inserted, or tray is opened\cr</span>
<span class="hl com">    CDS_AUDIO&amp; Audio disc (2352 audio bytes/frame)\cr</span>
<span class="hl com">    CDS_DATA_1&amp; data disc, mode 1 (2048 user bytes/frame)\cr</span>
<span class="hl com">    CDS_XA_2_1&amp; mixed data (XA), mode 2, form 1 (2048 user bytes)\cr</span>
<span class="hl com">    CDS_XA_2_2&amp; mixed data (XA), mode 2, form 1 (2324  user bytes)\cr</span>
<span class="hl com">    CDS_MIXED&amp; mixed audio/data disc\cr</span>
<span class="hl com">    }</span>
<span class="hl com">  $$</span>
<span class="hl com">  For some information concerning frame layout of the various disc</span>
<span class="hl com">  types, see a recent version of \cdromh.</span>
<span class="hl com"></span>
<span class="hl com">\item[CDROM_CHANGER_NSLOTS] Returns the number of slots in a</span>
<span class="hl com">  juke-box. </span>
<span class="hl com">\item[CDROMRESET] Reset the drive. </span>
<span class="hl com">\item[CDROM_GET_CAPABILITY] Returns the $capability$ flags for the</span>
<span class="hl com">  drive. Refer to section \ref{capability} for more information on</span>
<span class="hl com">  these flags.</span>
<span class="hl com">\item[CDROM_LOCKDOOR] Locks the door of the drive. $arg == \rm0$</span>
<span class="hl com">  unlocks the door, any other value locks it.</span>
<span class="hl com">\item[CDROM_DEBUG] Turns on debugging info. Only root is allowed</span>
<span class="hl com">  to do this. Same semantics as CDROM_LOCKDOOR.</span>
<span class="hl com">\end{description}</span>
<span class="hl com"></span>
<span class="hl com">\subsubsection{Device dependent $ioctl$s}</span>
<span class="hl com"></span>
<span class="hl com">Finally, all other $ioctl$s are passed to the function $dev_ioctl()$,</span>
<span class="hl com">if implemented. No memory allocation or verification is carried out. </span>
<span class="hl com"></span>
<span class="hl com">\newsection{How to update your driver}</span>
<span class="hl com"></span>
<span class="hl com">\begin{enumerate}</span>
<span class="hl com">\item Make a backup of your current driver. </span>
<span class="hl com">\item Get hold of the files \cdromc\ and \cdromh, they should be in</span>
<span class="hl com">  the directory tree that came with this documentation.</span>
<span class="hl com">\item Make sure you include \cdromh.</span>
<span class="hl com">\item Change the 3rd argument of $register_blkdev$ from</span>
<span class="hl com">$\&amp;&lt;your-drive&gt;_fops$ to $\&amp;cdrom_fops$. </span>
<span class="hl com">\item Just after that line, add the following to register with the \UCD:</span>
<span class="hl com">  $$register_cdrom(\&amp;&lt;your-drive&gt;_info);$$</span>
<span class="hl com">  Similarly, add a call to $unregister_cdrom()$ at the appropriate place.</span>
<span class="hl com">\item Copy an example of the device-operations $struct$ to your</span>
<span class="hl com">  source, \eg, from {\tt {cm206.c}} $cm206_dops$, and change all</span>
<span class="hl com">  entries to names corresponding to your driver, or names you just</span>
<span class="hl com">  happen to like. If your driver doesn&#39;t support a certain function,</span>
<span class="hl com">  make the entry $NULL$. At the entry $capability$ you should list all</span>
<span class="hl com">  capabilities your driver currently supports. If your driver</span>
<span class="hl com">  has a capability that is not listed, please send me a message.</span>
<span class="hl com">\item Copy the $cdrom_device_info$ declaration from the same example</span>
<span class="hl com">  driver, and modify the entries according to your needs. If your</span>
<span class="hl com">  driver dynamically determines the capabilities of the hardware, this</span>
<span class="hl com">  structure should also be declared dynamically. </span>
<span class="hl com">\item Implement all functions in your $&lt;device&gt;_dops$ structure,</span>
<span class="hl com">  according to prototypes listed in \cdromh, and specifications given</span>
<span class="hl com">  in section~\ref{cdrom.c}. Most likely you have already implemented</span>
<span class="hl com">  the code in a large part, and you will almost certainly need to adapt the</span>
<span class="hl com">  prototype and return values.</span>
<span class="hl com">\item Rename your $&lt;device&gt;_ioctl()$ function to $audio_ioctl$ and</span>
<span class="hl com">  change the prototype a little. Remove entries listed in the first</span>
<span class="hl com">  part in section~\ref{cdrom-ioctl}, if your code was OK, these are</span>
<span class="hl com">  just calls to the routines you adapted in the previous step.</span>
<span class="hl com">\item You may remove all remaining memory checking code in the</span>
<span class="hl com">  $audio_ioctl()$ function that deals with audio commands (these are</span>
<span class="hl com">  listed in the second part of section~\ref{cdrom-ioctl}). There is no</span>
<span class="hl com">  need for memory allocation either, so most $case$s in the $switch$</span>
<span class="hl com">  statement look similar to:</span>
<span class="hl com">  $$</span>
<span class="hl com">  case\ CDROMREADTOCENTRY\colon get_toc_entry\bigl((struct\ </span>
<span class="hl com">  cdrom_tocentry *{})\ arg\bigr);</span>
<span class="hl com">  $$</span>
<span class="hl com">\item All remaining $ioctl$ cases must be moved to a separate</span>
<span class="hl com">  function, $&lt;device&gt;_ioctl$, the device-dependent $ioctl$s. Note that</span>
<span class="hl com">  memory checking and allocation must be kept in this code!</span>
<span class="hl com">\item Change the prototypes of $&lt;device&gt;_open()$ and</span>
<span class="hl com">  $&lt;device&gt;_release()$, and remove any strategic code (\ie, tray</span>
<span class="hl com">  movement, door locking, etc.).</span>
<span class="hl com">\item Try to recompile the drivers. We advise you to use modules, both</span>
<span class="hl com">  for {\tt {cdrom.o}} and your driver, as debugging is much easier this</span>
<span class="hl com">  way.</span>
<span class="hl com">\end{enumerate} </span>
<span class="hl com"></span>
<span class="hl com">\newsection{Thanks}</span>
<span class="hl com"></span>
<span class="hl com">Thanks to all the people involved.  First, Erik Andersen, who has</span>
<span class="hl com">taken over the torch in maintaining \cdromc\ and integrating much</span>
<span class="hl com">\cdrom-related code in the 2.1-kernel.  Thanks to Scott Snyder and</span>
<span class="hl com">Gerd Knorr, who were the first to implement this interface for SCSI</span>
<span class="hl com">and IDE-CD drivers and added many ideas for extension of the data</span>
<span class="hl com">structures relative to kernel~2.0.  Further thanks to Heiko Ei{\sz}feldt,</span>
<span class="hl com">Thomas Quinot, Jon Tombs, Ken Pizzini, Eberhard M\&quot;onkeberg and Andrew</span>
<span class="hl com">Kroll, the \linux\ \cdrom\ device driver developers who were kind</span>
<span class="hl com">enough to give suggestions and criticisms during the writing. Finally</span>
<span class="hl com">of course, I want to thank Linus Torvalds for making this possible in</span>
<span class="hl com">the first place.</span>
<span class="hl com"></span>
<span class="hl com">\vfill</span>
<span class="hl com">$ \version\ $</span>
<span class="hl com">\eject</span>
<span class="hl com">\end{document}</span>
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